Embodiments herein generally relate to machines which transport and process print media and, more particularly, to a machine that incorporates a vacuum chamber within a print media transport device in order to maintain a print medium at a uniform predetermined distance from a print media processing device (e.g., an image printing device, an image scanning device, or a spectrophotometer) during processing.
As background, for machines that incorporate print media processing devices, such as image printing devices (e.g., inkjet printing devices), image scanning devices and/or spectrophotometers, the distance separating the print medium from the key processing component of the processing device must be uniformly and precisely maintained to prevent processing errors. For example, in an inkjet printing device, the distance separating the inkjet printing head and the print medium should remain constant to avoid registration errors. In an image scanning device, the distance separating the mirror assembly from the print medium should remain constant to avoid image capturing errors. In a spectrophotometer, the distance separating the spectral photometric sensor assembly from the print medium should remain constant to avoid light intensity measurement errors (i.e., image quality measurement errors). Existing machines incorporate print media transport devices (e.g., rolls with idlers, electrostatic belts, etc.) that do not sufficiently secure print media during processing to ensure that such a uniform distance is maintained, particularly when the leading and/or trailing edges of print media sheets are passed from one print media transport device to another.
In view of the foregoing, disclosed herein are embodiments of a machine which transports and processes print media. The machine incorporates a vacuum chamber within a print media transport device in order to maintain a print medium at a uniform predetermined distance from a print media processing device, such as an image printing device (e.g., an inkjet printer), an image scanning device, or a spectrophotometer). In one embodiment the vacuum chamber is located within a roller (e.g., a drive roller) that transports print media past the processing device. In another embodiment the vacuum chamber is located on an opposite side of a belt (e.g., an electrostatic belt) that transports print media past the processing device. In each of the embodiments the size of the vacuum chamber opening which defines the vacuum area on the transport device, and also the amount of vacuum pressure may be selectively adjusted depending upon the size and weight, respectively, of the print medium being processed.
More particularly, disclosed herein are embodiments of a machine which transports and processes print media. This machine can comprise a print media processing device. Exemplary print media processing devices can include, but are not limited to, image printing devices (e.g., inkjet printers), image scanning devices, and spectrophotometers.
In one embodiment, this machine can comprise a roller and a vacuum chamber within the roller. Specifically, the roller can be located in a position directly opposite the print media processing device and can transport a print medium past the processing device. The roller can comprise an axle. A support surface can encircle the axle and can be separated from the axle by a space. The support surface can have an outer side contacting the print medium and an inner side. The support surface can further have perforations extending from the outer side to the inner side. The vacuum chamber can be located within the roller and, particularly, within the space between the axle and the support surface. The vacuum chamber can have an open end adjacent a portion of the inner side of the support surface. This open end can be the processing device. The edges of this open end can define a vacuum area on the roller.
In operation, the vacuum chamber can apply vacuum pressure to a print medium that is being transported by the roller past the print media processing device. Specifically, the vacuum pressure emanates from the open end of the vacuum chamber through the perforations in the support surface of the roller and, thereby secures the print medium to the outer side of the support surface. In doing so, the vacuum pressure maintains the print medium at a uniform predetermined distance from the processing device as the print medium is transported, by the roller, past the processing device.
In order to ensure that the vacuum pressure will work as needed, the open end of the vacuum chamber should be aligned below the print medium as it passes the processing device. Furthermore, the width of the open end of the vacuum chamber (i.e., the first width) and the width of the print sheet (i.e., the second width) should be approximately equal. It should be understood that the first and second widths are to be measured in a direction perpendicular to the direction of travel of the print medium (i.e., measured in the cross-process direction). Additionally, a seal between the vacuum chamber and, more particularly, between the edges of the open end of the vacuum chamber and the inner side of the support surface can be used to prevent vacuum leakage that would limit how well the print medium is secured to the support surface of the roller.
Optionally, to ensure adequate control of print media having different sizes, the vacuum chamber can comprise at least one movable wall in order to allow the width of the open end of the vacuum chamber to be selectively adjusted based on the width of the print medium. The machine can be configured so that this selective adjustment process can be performed manually. Alternatively, the machine can be configured so that this selective adjustment process can be performed automatically. For example, the machine can further comprise one or more size sensors. The size sensor(s) can measure the width of the print medium. The machine can also further comprise a controller that is in communication with the size sensor(s) and operatively connected to the vacuum chamber. The controller can receive the width measurement from the size sensor(s) and can cause the movable wall(s) to move in order to ensure that the width of the open end is approximately equal to and aligned with the width of the print medium.
Also, optionally, to ensure adequate control of print media having different weights, the vacuum chamber can have different vacuum pressure settings that can be selectively adjusted (i.e., the vacuum pressure can be varied) based on the weight of the print medium. The machine can be configured so that this selective adjustment process can be performed manually. Alternatively, the machine can be configured so that this selective adjustment process can be performed automatically. For example, the machine can comprise a weight sensor. The weight sensor can measure the weight of the print medium. The machine can also further comprise a controller that is in communication with the weight sensor and that is operatively connected to the vacuum chamber. The controller can receive the weight measurement from the weight sensor, can determine the amount of vacuum pressure to be applied based on the measured weight, and can cause the vacuum chamber to apply the determined amount of vacuum pressure.
In another embodiment, the machine can comprise a belt transport device and a vacuum chamber within the belt transport device. Specifically, the belt transport device can be located in a position directly opposite the print media processing device and can transport a print medium past the processing device. The belt transport device can comprise, for example, at least two rollers and a belt supported and moved by the rollers such that the belt travels past the processing device. The belt can have an outer side contacting the print medium and an inner side contacting the rollers. The belt can further have perforations extending from the outer side to the inner side. The vacuum chamber can be located within the belt between the rollers such that as the belt travels it moves around the rollers and vacuum chamber. The vacuum chamber can have an open end adjacent a portion of the inner side of the belt. This open end can be facing the processing device. The edges of this open end can define a vacuum area on the belt.
In operation, the vacuum chamber can apply vacuum pressure to the print medium that is being transported by the belt past the print media processing device. Specifically, the vacuum pressure emanates from the open end of the vacuum chamber through the perforations in the belt and, thereby secures the print medium to the outer side of the belt. In doing so, the vacuum pressure maintains the print medium at a uniform predetermined distance from the processing device as the print medium is transported, by the belt, past the processing device.
In order to ensure that the vacuum pressure will work as needed, the open end of the vacuum chamber should be aligned below the print medium as it passes the processing device. Furthermore, the width of the open end of the vacuum chamber (i.e., the first width) and the width of the print sheet (i.e., the second width) should be approximately equal. It should be understood that the first and second widths are to be measured in a direction perpendicular to the direction of travel of the print medium (i.e., measured in the cross-process direction). Additionally, a seal between the vacuum chamber and, more particularly, between the edges of the open end of the vacuum chamber and the inner side of the belt can be used to prevent vacuum leakage that would limit how well the print medium is secured to the outer surface of the belt.
Optionally, to ensure adequate control of print media having different sizes, the vacuum chamber can comprise at least one movable wall in order to allow the width of the open end of the vacuum chamber to be selectively adjusted based on the width of the print medium. The machine can be configured so that this selective adjustment process can be performed manually. Alternatively, the machine can be configured so that this selective adjustment process can be performed automatically. For example, the machine can further comprise one or more size sensors. The size sensor(s) can measure the width of the print medium. The machine can also further comprise a controller that is in communication with the size sensor(s) and operatively connected to the vacuum chamber. The controller can receive the width measurement from the size sensor(s) and can cause the movable wall(s) to move in order to ensure that the width of the open end is approximately equal to and aligned with the width of the print medium.
Also, optionally, to ensure adequate control of print media having different weights, the vacuum chamber can have different vacuum pressure settings that can be selectively adjusted (i.e., the vacuum pressure can be varied) based on the weight of the print medium. The machine can be configured so that this selective adjustment process can be performed manually. Alternatively, the machine can be configured so that this selective adjustment process can be performed automatically. For example, the machine can comprise a weight sensor. The weight sensor can measure the weight of the print medium. The machine can also further comprise a controller that is in communication with the weight sensor and that is operatively connected to the vacuum chamber. The controller can receive the weight measurement from the weight sensor, can determine the amount of vacuum pressure to be applied based on the measured weight, and can cause the vacuum chamber to apply the determined amount of vacuum pressure.
Also, optionally, the machine can be configured so as to ensure that the vacuum pressure is only applied when needed and otherwise turned off. Specifically, the machine can further comprise one or more monitors monitoring the arrival of a leading edge of the print medium into the vacuum area and also the departure of a trailing edge of the print medium from the vacuum area. The machine can also comprise a controller in communication with the leading/trailing edge monitor(s) and operatively connected to the vacuum chamber. The controller can receive, from the monitor(s), notifications sheet arrival and departure and can cause the vacuum pressure to be turned on in response to the arrival of the leading edge of the print medium in the vacuum area and off in response to the departure of the trailing edge of the print medium from the vacuum area.
These and other features are described in, or are apparent from, the following detailed description.